in plasma-store/src/tests.rs [55:65]
fn plasma_client_create_and_seal() {
let pc = build_client();
let oid = ObjectId::rand();
let data = [1u8, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16];
let meta = [1, 2, 3, 4];
assert!(pc.create_and_seal(oid.clone(), &data, &meta).is_ok());
// creating an object with the same ID should result in an error
assert!(pc.create_and_seal(oid.clone(), &data, &meta).is_err());
}